Screen



y 1929- G. A. OVERSTROM 7 1,713,

. SCREEN Original Filed Sept. 28, 1920 risk 3 awwemtoz M 2551 .12)flbtomuf Patented May 14, 1929.-

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Original application filed September as, 1920, Serial no. 413,376.Divided and. this application filed March so, 1925.

My invention relates particularly to screens where a very high frequencyof vibration is employed to accomplish the desired results. Thisapplication is a division of my application Serial N 0. 413,376, filedSeptember 28, 1920, for vibrating screens, and relates particularly'tomeans forfastening andholding the screening cloth securely in place andwherein the screening cloth is quickly and easily replaced.

Other objects will appear hereinafter and I attain these objects by theconstruction illustrated in the accompanying drawing in which: a

Figure 1 is a cross section of a portion of a screen box illustratingthe'principles of my invention as applied to the stretching andfastening the screen cloth.

Fig. 2 is a sectional view in detail showing a method of fastening finescreen cloth to the stretching beams. v

Fig. 3 is a cross sectional view of a part of a screen box illustratinganother mode of 2e stretching and fastening the screening cloth.

Fig. 4 is a'transverse section taken'near one end of the screen box.

The same numerals refer to like parts throughout the several views.

In the operation of vibrating screens I have found that the longest lifeof the screen cloth, as well as the greatest capacity per square foot ofscreening surface and the least blinding of the screens-is obtained whenthe. as-screen cloth is stretched tight between the sides of a vibratingbox, and rigidly held to such box at the sides and ends only, allowing aclear unobstructed-flow over the screening surface without bolts, rivetsor otherpbstructions to hold the screen cloth to the vibrating member. j1

I have found also that where the sides of the screen cloth were rigidlyheld to a stationary frame, and the 'central'part of the wire-screencloth was attached to a vibrating member, not alone did the wires soonbreak near the vibrating connection bolts, but the whole screen clothwore rapidlypwhere the wires were in contact witheach other.Undoubtedly-this was caused by the-mechanical wreckingaction andabrasion due to the distortion of the position of the wires.

.I therefore naturally reached the conclu- .sionthat the wirescomprising the cloth must not be disturbed in relation to each other,but

Serial No. 19,201.

B0 ter of the screencloth prevented the even distribution of thematerial to be screened, especially 'if the feeddid not land exactly uniformly each side of such connections.

As argeneral rule, I operate my screens from 1500 to 2000 vibrations perminute,- and the vibrations may be about 1/16-inch diameter on finematerial, 1/8-inch on medium size and 3/l6-inch'or slightly over oncoarse as well as on moist material, on which less num-. ber ofvibrations and greater movement gives better results.

To effectively meet these and various other conditions under which thescreening operations are conducted and to permt ready replacement of theworn-out screens, I provide the construction herein disclosed. My inven-'tion accordingly includes special fastening devices which are capableof being variously utilized. As a specific example, however,illustrative of the principles of my invention applied toa screen boxwhich fulfills the above and other conditions, the screen box is made upof sides 1, to which are attached the top rails-'2 and the bottom rails3 provided withtie rods 7 on which are pipe struts 8 to hold the sidessecurely braced. The frame is held togther by nuts 9 on the ends of rods7 The end ties 5 and 6 hold-the sides 1 and the tie pieces firmlytogether. The supporting pipe 12 is held by clamps 11 and collars 13 areshrunk onto pipe 12. To the ends of pipe 12 arepressed spiral springs14, which are held in place by check nuts 15 on the ends of pipe 12. Thespiral springs 14are clamped 5 fast in the spring clamps 16 which arerigidly secured onto the stationar 'beams 18.

The screen cloth 52 is astened to stretching beams 53. .Stretching bolts54 serve to draw the beams 53 toward the sides 1 or bottom rail 3,thereby pulling the screen cloth drum tight.

In cases where wood is desirable for stretching beams, the constructionshown in Fig. 4 is used. The edges of the screen cloth are turned atright angles and the cloth held between cleats 55 and stretching beams53, the cleats being screwed on to the beams, thereby clamping the clothbetween the two. The turned sides of the cloth are also tacked tostretching beams 53 in case of the finer clot-h.

For stretching coarser and heavier cloth, steel channels and angles aremore frequently used, as shown in detail in Figs. 1, 2 and 3. In theupper part of Fig. 1 and in the lower part of Fig. 3 I have shownindependent wire stretchers, and in the lower part of Fig. 1 and theupper part of Fig. 3, I have shown twin stretchers for stretching,respectively, a single screen or double screens. In case of independentstretchers a single spacer 56 may be used. When the channels are used,they themselves form spacers.

Inside liners 57 serve to protect the sides 1 from wear, and also tohold down solidly the stretching beams 53 to the bottom rails 3-. Thewedges 58 which bear against the top rails 2, serve to press down theliners 57 The wedges are not driven home solidly until the screen clothis stretched.

When heavy screen cloth is used, it is only necessary to bend the sidesof the cloth over double or U-shaped, then slip the U over the flange ofthe channel or angle. When lighter cloth is used, I employ one or two Uclips, one 59 fitting inside the other 60, outside of the U-shaped sideof the screen cloth. This method effectually prevents slipping of thescreen cloth when stretching, but also allows of easily slipping theflimsy screen cloth into place without removing the stretching beamsfrom the screen box. In case of very fine bronze and brass screens, Isometimes only use the inside U clip and solder screen cloth 52 to theinside U Fig. 2.

clip 59 asshown at 61,

7 Where twin stretching is used in triple deck screens with sizes intandem or more as shown in diagram, Fig. 1, the cloths cannot be slippedin when stretching beams are in position, but the screens must be put onto the beams outside the box and then dropped in place. In that case anut 62 is riveted or welded to beams 53 and a tap bolt 63 employed forstretching. It would be impossible to put in bolts 54 in such asituation.

Having set forth the object and nature of my invention and variousconstructions embodying the principles thereof, what I claim as new anduseful and of my own invention and desire to secure by Letters Patent,is:

1. In vibrator structuresya screen box, a plurality of U-beams extendinglongitudinally of said box. screen cloths overlapping the edges of saidbeams and means for drawing said beam toward the sides of said box todraw said cloths taut, the width of said means forming means foraccurately spacing the cloths.

2. In a vibrator structure, a screen box having beams extendinglongitudinally thereof near the top and bottom, flanged beams extendingparallel to said beams, screen cloths overlapping said flanged'beams andmeans connected to said flanged beams for drawing said cloths tight, thewidth of said means forming means for accurately spacing the cloths.

In testimony whereof I have hereunto set my hand on this fourth day ofMarch, A. D.

GUSTAVE A. OVERSTROM.

